Authorities are alerting residents of a possible mountain lion sighting in Portola Valley this afternoon, a San Mateo County sheriff’s sergeant said.

Sgt. Bob Arnaudo said a resident reported seeing a mountain lion stalking a rodent in a field near Portola Road and Willowbrook Drive at about 3:30 p.m.

Responding deputies were unable to locate the cat but notified the state Department of Fish and Game as a precaution, Arnaudo said.

Residents in the area are advised to take precautions and report any further mountain lion sightings to the sheriff’s office.